Padstar
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| posted on 8/11/12 at 10:45 AM |
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Hidden welds
Just started welding my lower frame and have a few questions.
1) To what extent do I need to record the welds. As the frame is being fabricated by myself I guess the testers are going to want to go over it with a
fine toothed comb. Do I need to photo every joint as many of them will not be viable when complete.
2) how much can I "clean up" my welds. Have a few that don't look to great. Should I just leave them or is it ok to grind them back
to make more presentable.
3) do the welds need to be ground flush where bodywork and floor plates are going to be?
4) what's the best way to have a test of the sub frame for strength? Was thinking of a few axle stands at each corner and then stand on it but
was then thinking is it oly at full strength once the chasis is completed and will the lower rails just deflect ander stress until it is fully
complete?
Thanks for the help
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Chippy
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| posted on 8/11/12 at 11:26 AM |
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1/ You dont need to bother.
2/ Any crappy welds should be ground back and redone, IMHO.
3/ Yes, otherwise the plates wont fit nicely.
4/ The chassis will not achieve full strength untill it fully complete, you will just bend the bottom frame if you try what you have said.
Hope that helps. Cheers Ray
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
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b14wrc
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| posted on 8/11/12 at 12:22 PM |
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"2) how much can I "clean up" my welds. Have a few that don't look to great. Should I just leave them or is it ok to grind
them back to make more presentable. "
Can we see some photos?
Rob
20vt powered rear engined locost
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Padstar
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| posted on 8/11/12 at 02:18 PM |
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cant upload pics at the moment for some reason. Will try again latter.
In general should i not touch the welds, only where panels and floor plates need to be attached grind flush?
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Chippy
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| posted on 8/11/12 at 05:07 PM |
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Think I answered that in my first post! Cheers Ray
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
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Padstar
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| posted on 26/12/12 at 09:31 AM |
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Hi guys. Main part of the chassis is now complete with just plate sections to do. I have ground flat all welds that are on the outerside topside and
bottom of the chassis for the body panels and floor plates. If I plan to line the inside with carpet or ali should I do the same to the internal welds
to the cockpit.
My other concern (with being an able but still DIY welder) is how should one check the strength. Is there a way? My straight welds to 90% of the
joints I think are of a good quality but some appear a bit ropes to the internal joints of 90' joints. Should I grind and reweld? I really want
the chassis looking good before I powdercoat it but am starting to think I may be going ott and that my time could be better spent.
Given that about 10 of my friends and family have already said that they will not step foot in the car as I have built it is there any test that can
be done to prove the chassis is sound? I wouldn't mind this reassurance myself either.
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b14wrc
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| posted on 26/12/12 at 11:18 AM |
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I tried to validate my welding procedure prior to starting the car. I did several test pieces and cut them up to see penetration and fusion. I also
did the old hammer test!
Once I got good results, I knew my settings and method was good. My confidence is in that I did all this development. I am still considering using
some other NDE method to check once complete prior to powder coating. Check my posts on welding....
Rob
20vt powered rear engined locost
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Padstar
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| posted on 26/12/12 at 11:34 AM |
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Thanks mate. Had a good read of ur post before I started and did similar tests. All the sections I took the hammer to the metal bent before the weld
gave up so I guess I am worrying over nothing. Just I see this as my weakest ability out of the build so am maybe being overly cautious.
If u find any other way of testing then please let me know. Obviously the continuity is proven through being able to clamp the earth piece anywhere
and weld but this does cover the weld strength issue. Maybe I will just keep my fingers crossed
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coozer
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| posted on 26/12/12 at 01:15 PM |
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A good quality machine is the best way to weld heaven.
Over the years I've messed on with 100 and 150amp jobs but now have found a top quality welder is the way to go..
1972 V8 Jago
1980 Z750
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b14wrc
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| posted on 27/12/12 at 08:40 AM |
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Like Coozer just said, a good machine helps a lot. I upgraded my 105A SIP for a 170A Parweld, my welding improved so much with the bigger machine.
I will share any tips or NDE methods I use yes.
Rob
20vt powered rear engined locost
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Padstar
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| posted on 27/12/12 at 01:43 PM |
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I am using a 150amp machine so maybe that may not be helping but it was all the budget would stretch to.
Just found out one if my dads mates is a metal fabricator. He is going to pop round and give the chassis a once over and let me know his thaughts
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Peteff
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| posted on 27/12/12 at 05:00 PM |
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You can get good quality 100 or 150 amp machines just as you can get cheap rubbish ones. A friend of mine had a Clarke 150 amp which was a pleasure to
weld with once it had a decent earth clamp fitted. You need a low end of about 30 amps or less for thin metal like 16g tubing used for chassis build.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Padstar
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| posted on 28/12/12 at 11:43 AM |
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I have the Clarke 150 and it seems to work fine on thin metal.
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Padstar
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| posted on 3/2/13 at 08:15 AM |
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So the fabricated I mentioned came round yesterday and gave my chassis a thorough going over. Turns out he was rather impressed with my new found
welding skills. He highlighted a handfull of welds he has suggested I go back over using higher amps but generally these were my earlier welds.
He also said that the way the chassis is set up and all tied together he would be very surprised at a failure even if a weld had not fully
penetrated.
So a few more welds then I will be adding all the brackets to the frame. Starting to look like somethingnthatnresembles a car now
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b14wrc
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| posted on 20/3/13 at 09:19 PM |
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Photos??
20vt powered rear engined locost
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